HAGEN, Hermann August, entomologist, b. in Königsberg, Prussia, 30 May, 1817. For the last two hundred and fifty years some ancestor of his has been connected with the University of Königsberg. Young Hagen was graduated at the gymnasium in 1836, and received his medical degree from the university in his native city in 1840, also studying later in Berlin, Vienna, Paris, and elsewhere. Meanwhile he devoted considerable attention to entomology, and in 1834 published his first paper on “Prussian Odontata.” In 1843 he returned to Königsberg, entered on the general practice of medicine, and for three years was first assistant at the surgical hospital. From 1863 till 1867 he was vice-president of the city council and member of the school-board. While holding these offices he was invited by Louis Agassiz to come to Cambridge as assistant in entomology at the Museum of comparative zoölogy, and in 1870 was made professor of that science at Harvard. In 1863 he received the honorary degree of Ph. D. from the University of Königsberg, and he is a fellow of the American association for the advancement of science, besides being a member of other scientific societies. His publications include upward of four hundred articles, of which the most important is his “Bibliotheca Entomologica” (Leipsic, 1862).